Hello, I live in NY, and have a moisture problem with the two crawl spaces in my home, I have two additions on the house with crawl spaces under both. The one I am presently working on is a 10'x16' unheated, fully enclosed. porch. The previous owner apparently had this built some time ago. About a year after we purchased the house we realized that the floor was spongy, and sagging. Also the front wall was completely not attached to the sill plate (it had rotted away). A few months ago I removed the drywall, and found that on all three exterior walls the studs were completely dryrotted from 4' down. The floor was also dryrotted. The walls had 31/2 " bat type insulation with the vapor barrier facing in, and a plastic VB also facing in. The floor had no insulation, or VB. There was no plastic on the floor, of the crawl space, just dirt.
I have since replaced the floor, and walls. I have decided to heat this room, and was wondering how to keep the moisture off the wood. There is just one vent in the foundation, should I add another, or do I need any at all? I am not sure if the old windows were leaking, and that is what caused the walls to rot out, or if the moisture came up from the floor. The dirt in the crawl space does not seem to get real wet, but it is a little damp. I need to know if I should put down plastic on the dirt , or should I put small stones on the dirt, and then the plastic. I would also like to insulate the floor.
The rest of the house has a full basement, and that does get a little damp also. I am going do put on new gutters in the spring, and grade the ground around the foundation away from it. I am hopping this will take care of that problem.
I know that "The Insulator" had a lot of good post on this topic in the past, but I have been unable to find them as of yet.